The present invention relates to a method for generating a depth map of at least one selected region of a capturing region of a camera, and to a camera, a computing unit and a computer program for performing it.
Monitoring cameras are used for detecting suspicious objects or people, for counting people or for automatic monitoring of a specific region within the capturing region of the camera. In particular, sterile zones such as for example fences, external areas of buildings and the like are monitored. The field of use of such monitoring cameras, however, increasingly extends to public access regions, such as for example supermarkets, train stations, airports and the like.
In order to ensure robust tracking of objects in such scenes, the monitoring cameras can be calibrated. Typically suitable here is a calibration which calculates a relationship between 2-D image points and 3-D image points, the positions of which are located in the associated base plane. This information can be used to estimate real speeds and object sizes, for example in order to be able to calculate more stable object tracking in the camera image.
Depth information which extends beyond this, such as for example of objects located in the scene (for example obstacles, ramps, stairs, cabinets, objects placed on the ground, and the like), generally cannot be extracted easily with what is known as a single-camera system, i.e. a fixedly mounted monocular camera, as is typical for the field of video monitoring. However, this information is additionally useful in order to be able to develop further improvement and thus more robust systems with video content analysis (VCA).
In addition to static cameras, what are known as PTZ cameras can also be used in video monitoring, with PTZ being an acronym for pan, tilt and zoom. Such cameras may be fitted at one location so as to be stationary, while their camera system (optical system with an image sensor) is movable. This permits observation of different regions of a monitoring scene and thus gives a more flexible video monitoring option of the scene to be monitored.
DE 10 2013 223 995 A1 discloses for example a monitoring camera with which a depth map, i.e. a map with depth information (i.e. distance of an image point from a reference point, in particular from the camera), of a capturing region of the camera can be ascertained. Here, the camera is moved in space in order to be able to capture the capturing region from various observation angles, from which the depth map is then generated.